The Prevalence of CYP2B6 Gene Polymorphisms in Malaria-endemic Population of Timor in East Nusa Tenggara Indonesia

OBJECTIVES: The CYP2B6 is one of the most polymorphic CYP genes in humans that has the potential to modify the pharmacological and toxicological responses to clinically important drugs such as antimalarial artemisinin and its derivatives. The aim of the study was to determine the frequency of CYP2B6 polymorphisms in Timor malaria endemic area, East Nusa Tenggara, Indonesia where Artemisin-based Combination Therapy (ACT) has been used to treat uncomplicated malaria. METHODS: A total of 109 healthy subjects were participated in this study. CYP2B6*4, *6 and *9 polymorphisms were analyzed using PCR-RFLP to confirm the SNPs prevalence of 516G>T and 785A>G in exon 4 and 5. RESULTS: There were 96 subjects included in the analysis. In the exon 4 of CYP2B6 516G>T, the frequency of the T mutation was 37.5% (39/96), and the wildtype 27.1% (26/96). In the exon 5, CYP2B6 785A>G mutant was detected in 29.2% (28/96) of individuals, and the wildtype allele in 35.4% (34/96). The frequency of CYP2B6*9 (516G>T), CYP2B6*4 (785A>G) and CYP2B6*6 (516G>T and 785A>G) were 40.6%, 29.2% and 22.9%, respectively. The prevalence of these CYP2B6 gene polymorphisms in Timorian ethnic were higher than that in Malay, Han Chinese, Indian, and Egyptian populations. CONCLUSION: The prevalence of these CYP2B6 516G>T and 785A>G polymorphisms in Timorian ethnic is higher than that in other populations. These polymorphisms may affect the metabolism of artemisinin and its derivatives.

CYP2B6 516 G>T polymorphism and side effects of the central nervous system in HIV-positive individuals under Efavirenz treatment: Study of a sample from southern Brazil

ABSTRACT This study aimed to identify the 516 G>T polymorphism of the CYP2B6 gene and evaluate its influence on central nervous system (CNS) side effect development in HIV-positive individuals undergoing Efavirenz (EFV) treatment in a population from southern Brazil. Additionally, we performed a survey on the clinical and epidemiological characteristics of our sample. In addition to medical records evaluation, whole blood of 89 individuals was analyzed for viral load, T lymphocyte count (CD4+ and CD8+), and the polymorphism. Considering the side effects of the CNS reported by individuals but without considering the genetic variables, no statistically significant association was noted between the adverse effects and the antiretroviral treatment (including or not EFV). In addition, no statistically significant difference was noted for the influence of genotype on the viral load or the number of T lymphocytes (CD4+ and CD8+) among individuals undergoing EFV treatment. This is the first study that investigated the impact of the 516 G>T polymorphism of the CYP2B6 gene among HIV-positive individuals from southern Brazil. Its clinical significance indicates the need for prospective studies in this population.

Frequencies of Cytochrome P450 2B6 and 2C8 Allelic Variants in the Mozambican Population

Background: The cytochrome P450 enzymes (CYP) play an important role in the metabolism of many therapeutic agents. The activities of different enzymes exhibit variability in different populations, which causes variations in drug response or toxicity. The CYP2B6 and CYP2C8 enzymes are encoded by polymorphic genes characterised by different single nucleotide polymorphisms (SNPs). Several of these CYP variants are often associated with slow metabolism phenotypes. This study aimed to analyse the frequencies of allelic variants of CYP2B6 and CYP2C8 in the Mozambican population. Methods: Using a polymerase chain reaction and restriction fragment length polymorphism assay (PCR-RFLP), the frequencies of the allelic variants of CYP2B6 (c.64C>T, c.516G>T, c.777C>A, c.785A>G, c.1459C>T) and CYP2C8 (c.805A>T, c.416G>A, c.1196A>G, c.792C>G) were determined in 360 Mozambican blood donors. Results: The frequencies of the allelic variants of the CYP2B6 gene were 0.057, 0.426, 0.0, 0.410, and 0.004. For the CYP2C8 gene, the frequencies of the allelic variants were 0.160, 0.048, 0.0, and 0.005. No significant differences were observed between the gender and geographic distribution of volunteers around the country. Conclusion: The frequencies of the allelic variants of the CYP2B6 and CYP2C8 genes were found to be homogeneously distributed in the Mozambican population and were comparable to other African populations. Further studies are required to explore the impact of these variants on the clinical response (efficacy and toxicity) of drugs, including antimalarials.

Establishment of in vitro evaluation model for CYP2B6 induction and its application to screen inducers among TCMs / 药学学报

This paper is to report the development of a high-throughput in vitro system to screen hPXR/CAR mediated CYP2B6 drug inducers, and the application of it into the quick determination of induction activity toward CYP2B6 by various commonly used traditional Chinese medicines (TCMs) extract. Dual reporter gene assays were performed. The hPXR/CAR expression vectors and the reporter vector pGL3-CYP2B6-Luc involved in the distal and proximal promoters of CYP2B6 were co-transfected into HepG2 cells. Relative luciferase activities in cell lysate were analyzed after 48 h treatment of blank vehicle or drugs to determine the induction activity toward CYP2B6 by various commonly used TCMs extract. The positive hPXR/hCAR activators rifampicin and CITCO were applied to make sure that the reporter gene model was successfully established. Then 5 kinds of commonly used TCM extracts and 1 herbal compound were successfully investigated, some were found to activate hPXR or hCAR and therefore have the potential to induce CYP2B6 enzyme. This is the first domestic article to report the hCAR3-mediated CYP2B6 induction model and the establishment of a reporter gene system for hPXR/CAR-mediated CYP2B6 induction can be an effective and systemic in vitro method to investigate the drug inducers of CYP2B6 and to explain the mechanism involved.

Expression of cytochrome P450 related genes in oral submucous fibrosis tissue / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the expression of cytochrome P450 related genes in oral submucous fibrosis tissue and to investigate the possible role of the genes in pathogenesis of oral submucous fibrosis (OSF).</p><p><b>METHODS</b>Buccul mucosa tissues were obtained from OSF patients in early, medium and advanced stages, with each stage including 10 patients. Normal buccul mucosa tissues were collected from 10 patients undergoing oral and maxillofacial surgery as control. Oral submucous fibrosis-related genes were analysed by cDNA chips, and the results were submitted to the gene network database. Differentially expressed genes related to the pathway of CYP metabolism were indentifyed by the database analysis. Reverse transcription-polymerase chain reaction (RT-PCR) was used to verify the results from cDNA chips by increasing sample volume.</p><p><b>RESULTS</b>There were eight genes [CYP2B6, CYP2C18, CYP2F1, CYP3A5, microsomal glutathione S-transferase 2 (MGST2), alcohol dehydrogenase (ADH), UDP glucuronosyl transferase 2B15 (UGT2B15), ADH1C] which were related to the pathway of CYP metabolism. These genes were low expressed in all stages of OSF (P < 0.001).There were no differences in genes expression among the three stages of OSF (P > 0.05).</p><p><b>CONCLUSIONS</b>There were down-regulated genes related to the pathway of CYP metabolism in oral submucous fibrosis tissue. The ability of the pathway of CYP to metabolize and clear betel nut ingredients was reduced in OSF patients, which may play a role in the pathogenesis of OSF.</p>

Association between CYP2B6, CYP2D6, GSTP1 genetic polymorphisms and urinary styrene metabolites in professional workers / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To evaluate the influence of individual genetic polymorphisms of metabolic enzymes on urinary styrene metabolites.</p><p><b>METHODS</b>58 workers occupationally exposed to styrene were divided into the high exposure group (≥ 100 mg/m³) and the low exposure group (< 100 mg/m³). The microfluidic chip technology was used to determine the SNPs of CYP2B6, CYP2D6 and GSTP1 and the influence of gene polymorphisms on the metabolism of styrene was statistically analyzed.</p><p><b>RESULTS</b>The level of urine styrene metabolites level was influenced by genotypes of CYP2B6, CYP2D6 and GSTP1 [(280.28 +/- 100.60) mg/g Cr vs (183.48 +/- 127.52) mg/g Cr, (233.04 +/- 77.56) mg/g Cr vs (152.46 +/- 95.47) mg/g Cr, (32.88 +/- 7.14) mg/g Cr vs (24.47 +/- 5.59) mg/g Cr, P < 0.05)]. The metabolism of CYP2B6 G/G homozygotic genotype to styrene was more active than G/T heterozygotic genotype and T/T mutation genotype. The level of PHEMA in GSTP1 homozygotic genotype subjects was significantly higher than that in the group of homozygotic genotype [(32.07 +/- 7.32) mg/g Cr vs (25.59 +/- 6.95) mg/g Cr, P < 0.05)]. The influence of CYP2D6 genotypes on urinary metabolites was also observed in the same study [(56.36 +/- 109.72) mg/g Cr vs (177.13 +/- 116.21) mg/g Cr, (118.73 +/- 84.55) mg/g Cr vs (148.48 +/- 99.83) mg/g Cr, (18.29 +/- 13.50) mg/g Cr vs (19.95 +/- 13.30) mg/g Cr, P < 0.05)].</p><p><b>CONCLUSION</b>Genotypes of CYP2B6, GSTP1 and CYP2D6 are related to susceptibility to the metabolism of styrene in human.</p>

Effect of constitutive androstane receptor on the cytotoxicity of mitomycin C and 5-(aziridin-1-yl)-3-hydroxymethyl-1-methylindole-4,7-dione / 药学学报

This study is to evaluate the cytotoxicity of mitomycin C (MMC) and its analogue 5-(aziridin-1-yl)-3-hydroxymethyl-1-methylindole-4,7-dione (629) as well as the effect of transfection of constitutive androstane receptor (CAR) on their biological effects. HepG2 cells were transfected with the plasmids mCAR1/pCR3 mediated by liposome. Vector pCR3 was used as control. Transfected cells were screened by G418 resistance and limiting dilution. The expressions of plasmid mCAR1/pCR3 and CYP2B6 mRNA were detected by RT-PCR; Cytotoxicities of MMC and 629 in vitro were evaluated in g2car cells and HepG2 cells by MTT method under anaerobic and aerobic conditions. mRNA expression of CAR and CYP2B6 can not be detected in HepG2 cells and HepG2/pCR3 cells but can in g2car cells. It is shown that plasmid mCAR1/pCR3 was transfected into g2car cells successfully and target CYP2B6 was transactivated by CAR. To compare with aerobic and anaerobic, the cytotoxicities of MMC and 629 to HepG2 cells and g2car cells had significantly enhanced (P < 0.05), and transfect CAR gene can improve the cytotoxicity of MMC (P < 0.05), but not 629 (P > 0.05). Furthermore, CYP2B6 is one master enzyme for the metabolism of MMC and not 629. Transfection of CAR can increase expression of CYP2B6 mRNA in HepG2 cells, and can affect cytotoxicities of MMC and 629.